Semiconductor device

ABSTRACT

A semiconductor device includes a substrate, a multi-layer wiring layer formed on the substrate, and including a signal line and ground lines extending above the signal line, one of the ground lines extending toward a direction in a layer and another one of the ground lines extending from the one of the ground lines toward another direction in the layer, a first pad on the multi-layer wiring layer, and a redistribution layer formed on the multi-layer wiring layer, including a second pad, a redistribution line coupling the first pad and the second pad, and an insulation film covering the redistribution line.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation Application of U.S. patentapplication Ser. No. 13/490,871, filed on Jun. 7, 2012, which is aContinuation Application of U.S. patent application Ser. No. 12/929,968,now U.S. Pat. No. 8,237,287, which is based on and claims priority fromJapanese patent application No. 2010-080938, filed on Mar. 31, 2010, theentire contents of which is incorporated herein by reference.

The disclosure of Japanese Patent Application No. 2010-80938 filed onMar. 31, 2010 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to a semiconductor device having aredistribution layer.

2. Description of Related Art

System-in-package (SiP) technology for configuring a system of pluralsemiconductor chips (hereinafter referred to as “chips”) sealed in apackage has been known. A SiP includes plural ready-made chips stackedor horizontally arranged and sealed in a package. Depending on thearrangement of pads formed on each chip, therefore, routing of wires tobe bonded becomes complicated to possibly cause bonded wires to comeinto mutual contact. To avoid this problem, it sometimes becomesnecessary to change pad locations on individual chips before mountingchips for sealing as a SiP.

Redistribution layer (hereinafter referred to as “RDL”) technology isamong the means of changing pad locations. In RDL technology, aredistribution layer is formed over an existing chip. A redistributionlayer includes appropriately located new pads and redistribution linesfor coupling pads formed over an existing chip and the new pads. Thepads formed over a chip can be appropriately relocated making use of aredistribution layer formed over the chip. There is, however, a problemwith this technology. That is, circuits and signal lines formed over theexisting chip are adversely affected by electric field noise generatedby electric current flowing through the pads and redistribution linesformed over the redistribution layer. Technology for solving the aboveproblem is disclosed in Japanese Unexamined Patent Publication No.2005-005741.

FIG. 1 is a sectional view of the semiconductor device disclosed inJapanese Unexamined Patent Publication No. 2005-005741. Thesemiconductor device includes metallic parts 150 formed over theuppermost layer of a multilayer wiring layer 120 formed over a substrate110 over which capacitors 101 are formed. The multilayer wiring layer120 includes plural stacked layers each insulated with an interlayerinsulation film 130 and a wiring 140 formed over each of the stackedlayers. External terminals 400 and redistribution lines 500 are formedover an insulation film 300 which is formed over the multilayer wiringlayer 120. Each external terminal 400 is coupled to an electrode 200 ofa semiconductor chip 100 by a redistribution line 500.

FIG. 2 is a plan view of the semiconductor device disclosed in JapaneseUnexamined Patent Publication No. 2005-005741. Each metallic part 150 isformed in a region not included in any region where a wiring 140 isformed and is positioned upward of a capacitor 101 (or an analogcircuit). Each metallic part 150 is electrically coupled to a node 200kept at a predetermined potential.

In the semiconductor device disclosed in Japanese Unexamined PatentPublication No. 2005-005741, the electric field noise generated by theexternal terminals 400 and redistribution lines 500 formed over theredistribution layer is shielded by the metallic parts 150. Therefore,the possibility of the capacitors 101 being affected by the electricfield noise can be reduced. Also, since the metallic parts 150 can beformed in an existing process of forming the multilayer wiring layer120, they can be formed without largely increasing the total productionprocesses.

SUMMARY

In the semiconductor device disclosed in Japanese Unexamined PatentPublication No. 2005-005741, however, metal parts are formed along thelayout of external terminals and redistribution lines formed over aredistribution layer and, when the layout of external terminals andredistribution lines is changed, the metal parts cannot becorrespondingly relocated. Furthermore, each metal part is formed where,over the uppermost layer of a multilayer wiring layer, no signal linefor coupling to a circuit is formed. Thus, the layout of metal parts issubjected to restrictions imposed by the layout of multilayer wirings.

Means for solving the above problems will be described below referringto reference numerals used in the following “DETAILED DESCRIPTION OF THEPREFERRED EMBODIMENTS.” The reference numerals referred to serve toclarify correspondence between the appended claims and descriptions inthe “DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS.” The referencenumerals, however, should not be used for interpretation of a technicalscope of the invention defined by the appended claims.

A semiconductor device according to an aspect of the present inventionincludes a silicon substrate (21) over which a circuit (5) is formed, amulti-layer wiring layer (22) having a plurality of wiring layers (23 ato 23 c) formed over the silicon substrate (21) and a first pad (4)formed in a predetermined location of an uppermost layer of the wiringlayers (23 a to 23 c), a new pad (2) provided in an appropriate locationover the multi-layer wiring layer (22), and a redistribution layer (30)provided with a redistribution line (1) coupling the new pad (2) and thefirst pad (4). The multi-layer wiring layer (22) includes a signal line(6) for transmitting an electric signal to the circuit (5) and a groundline (3) provided between the redistribution line (1) or the new pad (2)and the circuit (5). The ground line (3) is formed to correspond to alocation where the new pad (2) is assumed to be located and a routealong which the redistribution line (1) is assumed to be formed. Theredistribution line (1) is formed along at least a portion of the groundline (3).

According to the present invention, the layout of signal lines andground lines is determined by taking into consideration assumed routesof redistribution lines and new pads assumed to be formed over aredistribution layer. Therefore, even when the layout of redistributionlines and new pads is changed, it is possible to deal with the change,so that the layout for the redistribution layer can be designed withincreased flexibility. Also, ground lines for shielding electric fieldnoise are not limited to an uppermost part of a multilayer wiring layer.For a multilayer wiring layer, therefore, signal lines and ground linescan be laid out with increased flexibility compared with cases wheresignal lines and ground lines are limited to an uppermost part of amultilayer wiring layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of the semiconductor device disclosed inJapanese Unexamined Patent Publication No. 2005-005741;

FIG. 2 is a plan view of the semiconductor device disclosed in JapaneseUnexamined Patent Publication No. 2005-005741;

FIG. 3 is a sectional view of a SiP including a semiconductor deviceaccording to a first embodiment of the invention;

FIG. 4 is a plan view of the semiconductor device according to the firstembodiment of the invention;

FIG. 5 is a plan view of a semiconductor device according to a secondembodiment of the invention;

FIG. 6 is a sectional view of the semiconductor device according to thesecond embodiment of the invention;

FIG. 7 is a plan view of a semiconductor device according to a thirdembodiment of the invention; and

FIG. 8 is a sectional view of the semiconductor device according to thethird embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A semiconductor device according to the present invention will bedescribed below with reference to the attached drawings.

First Embodiment

A semiconductor device according to a first embodiment of the presentinvention will be described below.

FIG. 3 is a sectional view, taken along line A-A″ in FIG. 4, of a SiPincluding the semiconductor device according to the first embodiment ofthe present invention. FIG. 4 is a plan view of the semiconductor deviceaccording to the present embodiment.

Referring to FIG. 3, a first semiconductor device 10 (hereinafterreferred to as a “semiconductor device 10”) is provided over a packagesubstrate 50. A second semiconductor device 20 (hereinafter referred toas a “semiconductor device 20”) is provided over the semiconductordevice 10. A redistribution layer 30 is formed over the semiconductordevice 20. The semiconductor devices 10 and 20 are sealed with a sealingresin 40 and make up a SIP. The configuration in which the semiconductordevice 20 is provided over the semiconductor device 10 as shown in FIG.3 is only an example. The semiconductor devices 10 and 20 may bearranged, for example, side by side over the package substrate 50.

The semiconductor device 20 is provided with a silicon substrate 21.Circuits 5 which may be, for example, transistors, are formed over thesilicon substrate 21. A multilayer wiring layer 22 including multiplewiring layers is formed over the silicon substrate 21. Even though, inthe present embodiment, the multilayer wiring layer 22 includes threewiring layers, i.e. a first wiring layer 23 a, a second wiring layer 23b, and a third wiring layer 23 c, the multilayer wiring layer 22 mayinclude more than or fewer than three wiring layers.

Each of the wiring layers includes signal lines 6 of, for example,aluminum (Al) or copper (Cu) and ground lines 3. The signal lines 6transmit electrical signals used for operations of the circuits 5. Theground lines 3 are coupled to a predetermined ground potential andshield electric field noise generated by the redistribution layer 30.First to third interlayer insulation films 24 a to 24 c of, for example,silicone dioxide are formed between the wiring layers. The signal lines6 and ground lines 3 may be intercoupled between different wiring layersvia through-holes 7.

The redistribution layer 30 is formed over the semiconductor device 20.Namely, redistribution lines 1 of, for example, aluminum (Al) or copper(Cu) are formed over the third interlayer insulation film 24 c formedover the uppermost layer of the multilayer wiring layer 22. Aninsulation film 31 of silicon dioxide (SiO2) or silicon nitride (SiN) isformed over the redistribution lines 1. The insulation film 31 iscovered with polyimide 32. New pads 2 are formed by removing appropriateportions of the insulation film 31 and polyimide 32 over thesemiconductor device 20. The redistribution lines 1 electrically couplepads 4 and the new pads 2 formed over the semiconductor device 20.

Of the new pads 2 formed over the redistribution layer 30 and the pads 4formed over the semiconductor device 20, appropriately located pads 4are coupled to lead electrodes formed over the package substrate 50 withbonding wires 60. Pads 11 are formed over the semiconductor device 10.The pads 11 are also coupled to lead electrodes formed over the packagesubstrate 50 with bonding wires 60. With the pads 4 formed over thesemiconductor device 20 being appropriately relocatable using the newpads 2 formed over the redistribution layer 30, the layout of thebonding wires 60 is prevented from becoming complicated.

The redistribution lines 1 and new pads 2 formed over the redistributionlayer 30 generate electric field noise when transmitting electricalsignals. The electric field noise adversely affects operations of thecircuits 5 and signal lines 6. As a measure against this problem, theground lines 3 are provided in portions, between the redistributionlines 1 and new pads 2 and the circuits 5 or signal lines 6, of themultilayer wiring layer 22. The ground lines 3 shield electric fieldnoise generated by the redistribution lines 1 and new pads 2 and,thereby, reduce the effects of the electric field noise on the circuits5 or signal lines 6. In the semiconductor device according to thepresent embodiment, the ground lines 3 are formed over any one of orplural ones of the wiring layers included in the multilayer wiring layer22. Therefore, the ground lines 3 can be laid out with increasedflexibility without being dependent on the layout of the signal lines 6.

FIG. 4 is a plan view of a configuration of not a specific layer butplural layers of the semiconductor device arranged to show portionsrequired to facilitate the following description.

Referring to FIG. 4, plural pads 4 a to 4 h are formed on the thirdwiring layer 23 c that is the uppermost layer of the multilayer wiringlayer 22 of the semiconductor device 20. Plural new pads 2 a to 2 d areformed in appropriate locations of the redistribution layer 30. Theredistribution lines 1 formed on the redistribution layer 30 couple pads4 and new pads 2. The circuits 5 are, as described in the foregoing,formed over the silicon substrate 21 of the semiconductor device 20. Theground lines 3 are formed in the multilayer wiring layer 22 of thesemiconductor device 20.

According to the present embodiment, the ground lines 3 are formed bytaking into consideration assumed locations of new pads 2 assumed to beformed, assumed routes of redistribution lines 1 assumed to be formed tocouple the assumed locations of new pads 2 and optional pads 4, and thelayout of the circuits 5 and signal lines 6. It must be noted that notall the ground lines 3 laid out have a new pad 2 and a redistributionline 1 formed over them. Namely, the ground lines 3 are deliberatelyformed in locations where a new pad 2 and a redistribution line 1 arepossibly formed.

For example, referring to FIG. 4, a redistribution line 1 is formedbetween the pad 4 a and new pad 2 a and also between the pad 4 b and newpad 2 b. The redistribution lines 1 are formed along and over thecorrespondingly located ground lines 3, but there are also ground lines3 formed in locations corresponding to no redistribution line 1.

Referring to FIG. 4, the ground lines 3 are formed to allow aredistribution line 1 to be formed to extend also from pad 4 c, 4 f, or4 g. Reference numerals 2 c and 2 d in FIG. 4 represent locations wherenew pads 2 (2 c and 2 d) were assumed to be formed, though not realized.Namely, when new pads 2, e.g. 2 c and 2 d, are assumed to be provided,the ground lines 3 are formed taking into consideration the assumedlocations of the new pads 2 c and 2 d.

A designer when designing the semiconductor device 20 determines thelayout of the ground lines 3 and signal lines 6 to be formed in themultilayer wiring layer 22 by taking into consideration the assumedlocations and routes of new pads 2 and redistribution lines 1 assumed tobe formed over the redistribution layer 30. For example, the groundlines 3 may be laid out in a grid-like pattern allowing pads 4 and newpads 2 to be coupled and the signal lines 6 may be laid out to beoutside the area where the ground lines 3 are laid out. This makes itpossible, when a layout design for new pads 2 and redistribution lines 1assumed to be formed is changed, to deal with the change. The groundlines 3 can be formed, as described above, over any one of or some ofthe wiring layers included in the multilayer wiring layer 22, so thatthey can be laid out with increased flexibility.

The semiconductor device according to the first embodiment of thepresent invention has been described above.

Second Embodiment

A semiconductor device according to a second embodiment of the presentinvention will be described below. The semiconductor device according tothe second embodiment differs from that according to the firstembodiment in layout of ground lines 3.

FIG. 5 is a plan view of the semiconductor device according to thesecond embodiment. FIG. 6 is a sectional view, taken along line A-A″ inFIG. 5, of the semiconductor device according to the second embodimentof the present invention.

In the semiconductor device 20 shown in FIG. 5, ground lines 3 are laidout along the outer periphery of the semiconductor device 20. This isbecause new pads 2 are, as exemplified by new pads 2 a and 2 b,generally arranged near the outer periphery of the semiconductor device20. With the ground lines 3 laid out along the periphery of thesemiconductor device 20, new pads 2 can be located anywhere along theperiphery of the semiconductor device 20.

Referring to FIG. 6, the ground lines 3 are formed over the secondwiring layer 23 b included in the multilayer wiring layer 22. As in thefirst embodiment, the ground lines 3 may be formed over any one of orsome of the plural wiring layers 23 a to 23 c included in the multilayerwiring layer 22. They may also be formed to extend across the pluralwiring layers 23 a to 23 c. With the ground lines 3 laid out asdescribed above, even when the circuits 5 or signal lines 6 are formed,as shown in FIG. 6, near the periphery of the semiconductor device 20,the electric field noise generated by the new pads 2 can be shielded.

Also, as shown between the pad 4 b and the new pad 2 b in FIG. 5, layingout a ground line 3 along an assumed route of a redistribution line 1 asin the first embodiment makes it possible to shield the electric fieldnoise generated by the redistribution line 1 between the pad 4 b and thenew pad 2 b. The ground lines 3 may also be laid out in a grid-likepattern as in the first embodiment so that pads 4 a to 4 h can becoupled to new pads 2.

In connection with both the first and second embodiments, there can becases where no ground line 3 is formed along the route of aredistribution line 1, for example, between the pad 4 a and the new pad2 a as shown in FIG. 5. Such condition occurs, for example, when nocircuit 5 and no signal line 6 is formed in a location corresponding tothe route of a redistribution line 1 or new pad 2 over the siliconsubstrate 21. In such a case where no circuit 5 and no signal line 6which can be affected by electric field noise is formed in a locationcorresponding to the route or location of a redistribution line 1 or newpad 2, the presence of no ground line 3 over such route or location doesnot cause any problem. When, for example, circuits 5 or signal lines 6which can be affected by electric field noise are located to correspondto only a portion of the route or location of any redistribution line 1or new pad 2, a ground line is required to be formed to shield electricfield noise at least from such a portion.

The semiconductor device according to the second embodiment of thepresent invention has been described above.

Third Embodiment

A semiconductor device according to a third embodiment of the presentinvention will be described below. The semiconductor device according tothe third embodiment differs from those according to the first andsecond embodiments in layout of ground lines 3.

FIG. 7 is a plan view of the semiconductor device according to the thirdembodiment. FIG. 8 is a sectional view, taken along line A-A″ in FIG. 7,of the semiconductor device according to the third embodiment of thepresent invention.

In the third embodiment, as shown in FIG. 7, the portion correspondingto the redistribution line 1 between the pad 4 a and the new pad 2 a ofthe ground lines 3 is wider than the corresponding portion of the groundlines 3 of the first embodiment. Normally, when a ground line 3 isformed between a redistribution line 1 or new pad 2 formed over an upperlayer and a circuit 5 formed over a lower layer, the ground line 3 ismade wider than, that is, larger in area than the redistribution line 1and new pad 2. Namely, the ground lines 3 are more effective inshielding electric field noise when they are larger in area.

Depending on the positional relationship between redistribution lines 1formed over an upper layer above the ground lines 3 and circuits 5 andsignal lines 6, a large parasitic capacitance is formed between them.Such a large parasitic capacitance can affect the electrical propertiesof the circuits. To avoid such a problem, when designing thesemiconductor device 20, the designer determines the layout of groundlines 3 so as to make the ground lines 3 larger in area by taking intoconsideration assumed locations of new pads 2 and assumed routes ofredistribution lines 1 and also considering the layout of signal lines6. At this time, the ground lines 3 are made as wide as possible withinrestrictions related with overall layout and circuit characteristics.This makes it possible to shield electric field noise more effectively.

The semiconductor device according to the third embodiment of thepresent invention has been described above.

As described above, in the semiconductor device 20 to be provided with aredistribution layer 30, ground lines 3 are formed in locations, of amultilayer wiring layer 22 of the semiconductor device 20, correspondingto the assumed locations and routes of new pads 2 and redistributionlines 1 to be possibly formed over the redistribution layer 30. In thisway, even when the locations or routes of new pads 2 or redistributionlines 1 are changed, it is possible to deal with the change.

The ground lines 3 are formed between the new pads 2 and redistributionlines 1 formed over the redistribution layer 30 and the circuits 5 andsignal lines 6 formed over the silicon substrate 21 so as to shieldelectric field noise generated by the new pads 2 and redistributionlines 1. The ground lines 3 are formed over one of the plural wiringlayers 23 a to 23 c of the multilayer wiring layer 22 or across some ofthe plural wiring layers. The ground lines 3 can therefore be laid outwith increased flexibility.

The foregoing embodiments can be carried out whether individually or incombination.

The present invention has been described by way of embodiments, but theinvention is not limited to the embodiments. The configuration anddetails of the invention can be modified in various ways by thoseskilled in the art without departing from the scope of the invention.

What is claimed is:
 1. A semiconductor device, comprising: a substrate;a multi-layer wiring layer formed on the substrate, and including asignal line and ground lines extending above the signal line, one of theground lines extending toward a direction in a layer and another one ofthe ground lines extending from the one of the ground lines towardanother direction in said layer; a first pad on the multi-layer wiringlayer; and a redistribution layer formed on the multi-layer wiringlayer, including a second pad, a redistribution line coupling the firstpad and the second pad, and an insulation film covering theredistribution line.
 2. The semiconductor device according to claim 1,wherein the redistribution line extends above the ground lines along theone of the ground lines.
 3. The semiconductor device according to claim2, wherein the insulation film includes a hole exposing the second padabove an end portion of the one of the ground lines.
 4. Thesemiconductor device according to claim 3, wherein the insulation filmdoes not include any of holes above an end portion of the another one ofthe ground lines.
 5. The semiconductor device according to claim 1,wherein the another one of the ground lines extends in a directionperpendicular to the one of the ground lines.
 6. The semiconductordevice according to claim 1, wherein the one of the ground lines iswider than the another one of the ground lines.
 7. The semiconductordevice according to claim 1, wherein the another one of the ground linesextends along an outer periphery of the multi-layer wiring layer.
 8. Thesemiconductor device according to claim 1, further comprising a bondingwire coupled to the second pad.